#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
using mint = modint1000000007;
#define rep1(a)          for (int i = 0; i < (a); i++)
#define rep2(i, a)       for (int i = 0; i < (a); i++)
#define rep3(i, a, b)    for (int i = a; i < (b); i++)
#define rep4(i, a, b, c) for (int i = a; i < (b); i += c)
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
using ll = long long;
constexpr ll INF = (1LL << 60);
void chmax(ll& a, ll b) { a = max(a, b);}
void chmin(ll& a, ll b) { a = min(a, b); }
inline void YesNo(bool ok) {
  cout << (ok ? "Yes\n" : "No\n");
}
template<class T>
void input_vec(vector<T>& v) {
  for (auto& x : v) cin >> x;
}
template<class... T>
void input(T&... a) {
  (cin >> ... >> a);
}
void print() {
  cout << '\n';
}
template<class T, class... Ts>
void print(const T& a, const Ts&... b) {
  cout << a;
  (cout << ... << (cout << ' ', b));
  cout << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int T;
  cin >> T;
  rep(i, T) {
    int N;
    ll K;
    cin >> N >> K;
    vector<ll> A(N);
    rep(j, N) cin >> A[j];
    ll ans = LONG_LONG_MAX;
    rep(j, N) {
      ll temp = 1;
      rep(k, N) {
        if (k == j) temp *= (A[k] - K);
        else temp *= A[k];
      }
      ans = min(ans, temp);
    }
    cout << ans << endl;
  }
  return 0;
}